Yinlong Hu

Performance Benefits of Using Inerter in Semiactive Suspensions

This brief investigates the performance benefits of using inerter in semiactive suspensions. A novel structure for semiactive suspensions with inerter, which consists of a passive part and a semiactive part, is proposed. Six semiactive suspension struts, each of which employs an inerter in the passive part and a semiactive damper in the semiactive part, are introduced. Two suboptimal control laws named clipped optimal control and steepest gradient control laws are derived to control the damping coefficient in the semiactive part. Extensive simulations with respect to different choices of weighting factors and suspension static stiffnesses are conducted based on both a quarter car model and a full car model. The results show that, compared with the conventional semiactive suspension strut, the overall suspension performance can be significantly improved using inerters, including ride comfort, suspension deflection, and road holding. Comparative studies between these two suboptimal control laws and between these semiactive struts are also carried out to facilitate future practical application of the proposed semiactive suspensions with inerter.

Suspension performance with one damper and one inerter

In Chen & Smith 2009, a class of realizations in which the number of dampers and inerters is restricted to one in each case, while allowing an arbitrary number of springs (which is the easiest element to realize practically), was considered and it was proven that at most four springs are needed-an explicit construction was given comprising five different circuit arrangements to cover all cases. This paper makes a comparative study of the performances of these five circuit arrangements when applied as mechanical suspension struts in a quarter-car model.

Semiactive Inerter and Its Application in Adaptive Tuned Vibration Absorbers

This brief presents a novel framework to realize the semiactive inerter, and proposes a novel semiactive-inerter-based adaptive tuned vibration absorber (SIATVA). The proposed semiactive inerter can be realized by replacing the fixed-inertia flywheel in the existing flywheel-based inerters with a controllable-inertia flywheel. Then, by using the proposed semiactive inerter, an SIATVA is constructed, and two control methods, that is, the frequency-tracker-based (FT) control and the phase-detector-based (PD) control, are derived. The experimental results show that both the FT control and the PD control can effectively neutralize the vibration of the primary mass, although the excitation frequency may vary. The proposed SIATVA can also tolerate the parameter variation of the primary system. As a result, it can be applied to a variety of primary systems without resetting the parameters. The performance degradation by the inherent damping is also demonstrated.

Semi-active suspension with semi-active inerter and semi-active damper

Abstract This paper investigates the application of semi-active inerter in semi-active suspension. A semi-active inerter is defined as an inerter whose inertance can be adjusted within a finite bandwidth by on-line control actions. A force-tracking approach to designing semi-active suspension with a semi-active inerter and a semi-active damper is proposed, where the target active control force derived by LQR control in the “Reciprocal State-Space” (RSS) framework is tracked by controlling the semi-active damping coefficient and semi-active inertance. One of the advantages of the proposed method is that it is straightforward to use the acceleration information in the controller design. Simulation results demonstrate that the semi-active suspension with a semi-active inerter and a semi-active damper can track the target active control force much better than the conventional semi-active suspension (which only contains a semi-active damper) does. As a consequence, the overall performance in ride comfort, suspension deflection and road holding is improved, which effectively demonstrates the necessity and the benefit of introducing semi-active inerter in vehicle suspension.

Semi-active suspensions with low-order mechanical admittances incorporating inerters

This paper investigates the application of inerters in semi-active suspensions. An approach to designing semi-active suspension with inerter is proposed by dividing the semi-active system into a passive part and a semi-active part. The passive part is a mechanical network consisting of springs, dampers and inerters; the semi-active part is a semi-active damper. Different from the existing result using some fixed-structure networks as the passive part, in this study, the passive part is obtained by optimizing some low-order admittance functions and then by realizing the optimized admittance functions as mechanical networks. A suboptimal control law named steepest gradient control is employed for the semi-active damper in the semi-active part. The proposed method is illustrated in a quarter-car vehicle system, and the effectiveness of the proposed method is demonstrated by using numerical simulations. It is shown that significant improvement can be obtained by using the proposed method compared with the conventional semi-active suspensions without inerter.

Effect of play in inerter on vehicle suspension system

The inerter is a recently proposed two-terminal element, where the force across the two terminals is proportional to their relative acceleration. Studies have demonstrated the performance improvement of suspension systems when incorporating inerters. This paper focuses on the influence of a play, usually used to model an undesirable clearance at the contact between elements, in the inerter on a vehicle suspension system. A quarter car model and a full car model are built using MATLAB SimMechanics. Using the model, simulations of the suspension system are performed in both the frequency and time domains, evaluating performances of the suspension with different play parameters. Based on these results, the influence of a play is analysed, demonstrating an improvement under a certain condition.